Film-Tech Forum ARCHIVE: Stuck pixel during DLP presentation

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Posted by Aaron Haney (Member # 747) on 07-16-2008, 08:35 PM:

This past Sunday I went to the first DLP presentation I've been to in a while, and there was a stuck pixel visible throughout the entire show. It took the form of a bright blue dot near the center of the screen. Very annoying. It was only present during the trailers and feature, not during the pre-show (which was clearly running from a separate system).

Is there anything the theater can do about this, short of replacing the projector?

Theater management was informed, but the response was not encouraging. We got a couple of free passes out of it, and it was made clear we were lucky to get that. I have serious doubts anything will be done.

In case anyone is wondering, it was auditorium number 6 at the Century at Tanforan in San Bruno, CA.

Posted by Mark Gulbrandsen (Member # 72) on 07-16-2008, 08:51 PM:

Possibly, but they will have to call in a tech to see. It is sometimes possible to free up a stuck pixel(s) by exerising the DMD's. We recetly conducted a Christie DLP training class at CLACO and the instructor mentioned something about doing this.... I believe he said there is a test pattern in the latest or last version of the T.I. Software tht can be used for excercising the pixels... they are pulse width modulated! If its the DMD that does turn out to be defective then you replace the light engine assembly not the entire projector. It may also still be under warranty.

Mark

Posted by Joe Redifer (Member # 3) on 07-16-2008, 10:22 PM:

quote: Aaron Haney
We got a couple of free passes out of it, and it was made clear we were lucky to get that.

Sounds like the customer service sucks at the Century at Tanforan in San Bruno, CA. What a horrible theater. They do not deserve to be in business if they are telling you that you are "lucky" to get passes even when their equipment is broken. Do not go to that theater ever again. If you use your free passes, do NOT purchase concessions. Write their corporate headquarters and see if anyone who works there actually cares (don't get your hopes up).

The manufacturers of DLP equipment had better come up with a solution fast. How pathetic is a stuck pixel?

Posted by Mark Gulbrandsen (Member # 72) on 07-16-2008, 10:32 PM:

quote: Joe Redifer
The manufacturers of DLP equipment had better come up with a solution fast. How pathetic is a stuck pixel?

Ha! Its about as pathetic as a scratched filum print... for which filum manufacturers never came up with a solution for either.

Posted by Joe Redifer (Member # 3) on 07-16-2008, 10:52 PM:

A sloppy projectionist doesn't cause a stuck pixel. Also, once that scratched print is replaced, scratch is gone. Stuck pixel shows on every show FOREVER until fixed. What a horrible analogy. You should have compared it to a chipped lens or a torn screen instead. Ooops, that can happen on DLP as well!

Posted by Geoff Jones (Member # 3668) on 07-17-2008, 12:18 AM:

Heh - I had that exact same problem with my LCD projector (Sanyo PLV-60HT) at home. The first unit I got had a blue pixel stuck "on."

I lived with it for a few days (hoping maybe it would get unstuck?), until I had friends over to watch The Terminator. Friend's wife: "Oh look, the blue dot is on Arnold's pee-pee now." The projector went back in the mail immediately and I got the vendor to inspect the next unit before they shipped it.

Oh, and I saw a brand new 35mm print of The Terminator this year at a packed house at the Castro Theatre and it ROCKED. Long live film!

Posted by Aaron Haney (Member # 747) on 07-17-2008, 12:46 AM:

They did not actually use the word "lucky", but there was a clear resistance to doing anything and general lack of concern. I certainly don't plan on returning to that location.

Also, I think it's unfair to compare this problem to print damage such as scratches or dirt. The blue dot was visible on every single frame of the movie, yet it's beyond rare that I've seen scratches or dirt that covered every single frame of a print, or even close to it. I can easily ignore dirt and scratches because I know they are almost always gone quickly. A bright blue speck in the middle of the screen that stays for the entire duration of the feature is quite different. The person who attended the movie with me agreed -- they are normally not bothered by minor problems, but found this very annoying.

Posted by Andy Frodsham (Member # 4061) on 07-17-2008, 06:34 AM:

Wow, for some, seemingly, naive reason, I didn't think that commercial digital projectors would be prone to this 'stuck pixel' problem! Don't ask me why I thought this way - possibly the cost of the units and the fact that this technology is being hailed as the best thing since sliced bread!

This must inevitably pose massive potential problems for the system?

I'm not gloating - honestly!

Posted by Stephen Furley (Member # 1277) on 07-17-2008, 07:21 AM:

quote: Mark Gulbrandsen
If its the DMD that does turn out to be defective then you replace the light engine assembly not the entire projector. It may also still be under warranty.

How much does that cost, assuming that it's not under warrenty? How long is the warrenty? How long is the typical life of these devices? How much would you expect to pay for a maintenance contract that would include replacement of these if they do fail?

Posted by Mark Gulbrandsen (Member # 72) on 07-17-2008, 09:17 AM:

quote: Stephen Furley
How much does that cost, assuming that it's not under warrenty?

ALOT!

quote: Stephen Furley
How long is the warrenty?

Thats up to the customer. We've sold extended warranties on all the Christie's we've sold... So that makes the manufacturers warranty 5 years. I don't know if the other DLP manufacturers offer extended warranties at all but Christie sells extended warranties in 2 year increments at the time of purchase.

quote: Stephen Furley
How much would you expect to pay for a maintenance contract that would include replacement of these if they do fail?

Maintainance contracts rarely include parts costs however you can get insurance for this sort of thing.

To me a stuck pixel would also be very annoying but so is the common printer bounce we see in almost every print struck today.

Mark

Posted by Jim Cassedy (Member # 4115) on 07-17-2008, 10:44 AM:

I haven't been to the Century Tanforan 6 yet, but have driven by it several times on my way to the airport.

That's interesting about the stuck pixel.
The Century 6 Tanforan has been open less than 6 months and took out full-page color centerfold advertisements in several of the local San Francisco Bay area newspapers the weekend they opened proclaiming that all their auditoriums used "superior" digital projection.

A bit of history for those outside of the SF Bay area-
Century 6 is located in a shopping center that sits on the site of the former Tanforan race track.(horse racing)

During WWII, the Tanforan track was also used as a 'holding and processing area' for Japanese-Americans before they were shipped off to internmant camps.

I understand that it was a different time, place and set of circumstances, but I've never visitied that mall or had any desire to see the new "superior" Century 6 just because the whole place made me uncomfortable.

Posted by Frank Angel (Member # 248) on 07-17-2008, 01:35 PM:

Most scratches and dirt are intermittent. Stuck pixels are steady-state and MUCH more annoying. Scratches and dirt come from poor handling of the film, not from the projector. You can change a damaged print; it's a lot more costly to replace that DLP nano mirror module. And this is only a few years out. At least with a 35mm film projector, you don't expect to find its weaknesses showing up this early on.

Look, there is NO technology that is perfect. There are going to be weaknesses. With digital, the maintenance costs to keep ahead of them showing up is much more costly than with a film based system. Stuck or dead pixels are inherent in the video display technology, so someplace along the line those specks of light or black are going to start to populate digital projector displays, the question is how soon and how costly will it be to repair them.

Second question is, those same theatre operators who wouldn't foot the cost to buy a supply of Film Guard and a Kelmar cleaner to prevent dirt and scratches or who let bulbs burn to the point were the picture is barely visible, they're THE SAME GUYS running the digital booths. How reluctant will these owners be to replace a very expensive malfunctoning nano-mirror module? Only time will tell, but I wouldn't put any bets on theatre owners stepping up to the plate when digital equipment starts to show its age. The big problem is that it may very well start showing its age long before a 35mm projector shows it's flaws.

The digevangelists were always comparing how images looked when the DLPs were newly tweaked and practically out of the box against old 35mm equipment that had been running in theatres for decades. It wasn't a fair comparison. Sure, you can plop a new $100,000 digital projector system in a theatre that's been run poorly and it will fix a multitude of sins -- for the moment, but it is still in a theatre that is RUN POORLY. The equipment won't change that. Sooner or later the neglect that made 35mm look bad there will impact the digital there as well. And since digital will cost ALLOT more to repair, it is foolish to think these operators will give any more of a rats ass about presentation than they did with their 35mm systems -- extended warantees not withstanding.

BTW, extended warantees don't make it any less expensive to repair or replace these modules -- it only shifts the cost, and whoever is absorbing that cost is going to pass it back onto the end user one way or another. The cost of having a technician come in to replace failing DMDs is much more than a tech coming in to repair an mechanical intermittent.

Posted by Mark Gulbrandsen (Member # 72) on 07-17-2008, 05:38 PM:

I'm still sort of chuckling at how everyone assumes this is a stuck pixel while there are at least a few other things that can cause a blemish like this in the image. Integrator rod, Fold Mirror, lens, etc. None of these are all that expensive to repair. And yes, when a print is scratched on a platter system its usually all the way through and the booth jockey had no idea that it was being scratched. Perhaps this says something in favor of Guttag's reels. Indeed, no system is perfect nor should it be as we'd all be out of buisness.

Posted by Aaron Haney (Member # 747) on 07-19-2008, 01:44 AM:

The lens could have caused it? Huh?

It was a small dot in sharp focus, just the right size to be a pixel, and it remained full brightness even when the entire rest of the image went black. It was also strongly blue, one of the component colors of the 3-chip system.

The fact that it always remained at full brightness is by itself enough to rule out most other possibilities I would think, especially anything in the light path prior to the DLP chips (otherwise it would have gone dark along with the rest of the image whenever there was a fade to black).

And for the record, the last time I saw a scratch on a 35mm print, it lasted less than a minute.

Posted by Stephen Furley (Member # 1277) on 07-19-2008, 03:38 AM:

Mark,

In rough terms how much would you say it costs, per year, to run a typical digital projector?

Posted by Mark Gulbrandsen (Member # 72) on 07-19-2008, 09:30 AM:

quote: Aaron Haney
The lens could have caused it? Huh?

The integrator could have easily caused that problem. If you've ever seen an integrator fail you'd know what I mean.

quote: Stephen Furley
In rough terms how much would you say it costs, per year, to run a typical digital projector?

Actually, it depends on the screen size but assuming that you'd be running a 3 or 4 kw for film the cost is very close and lamp life is not that different if you have to use short gap lamps. In fact Christie rates the CDXL-30 in a ZX projector at 2500 hours. Most of our installs with the exception of the Zion Canyon location use regular cinema lamps. Zion uses a CDXL60. When they install their new silver screen they will go down at least one lamp size. If they choose to run stacked 2-D they could easily run with a CDXL30 in each CP-2000.

Mark

Posted by Jack Ondracek (Member # 1466) on 07-19-2008, 02:18 PM:

quote: Aaron Haney
They did not actually use the word "lucky", but there was a clear resistance to doing anything and general lack of concern. I certainly don't plan on returning to that location.

The manager is probably some poor, underpaid schlub, working for a company that has expressed no desire to fix the problem. You are probably the 4,753rd person to bring the stuck pixel to his attention. He's likely resigned to this being an everlasting part of his employment. He can't do anything about it, and is probably tired of apologizing for his employer. You got your passes. Just go to a different screen.

Posted by Todd McCracken (Member # 4718) on 07-21-2008, 02:36 PM:

Either that or its a circuit that dosent have a maintenance contract. Equipment in the digital realm is quite expensive to fix in such instances.

Posted by Mark Gulbrandsen (Member # 72) on 07-21-2008, 05:10 PM:

quote: Todd McCracken
Equipment in the digital realm is quite expensive to fix in such instances.

Integrator rods cost less then the price of a decent used lens. Its also possible that the equipment is still under warranty... its obvious they just don't give a crap... their film presentations must have really sucked!

Mark

[ 07-21-2008, 07:28 PM: Message edited by: Mark Gulbrandsen ]

Posted by Mike Blakesley (Member # 26) on 07-21-2008, 05:59 PM:

quote: Mark Gulbrandsen
they just don't gove a drap

Hitting the sauce a little early today, eh Mark? [beer]

Posted by Mark Gulbrandsen (Member # 72) on 07-21-2008, 07:29 PM:

quote: Mike Blakesley
Hitting the sauce a little early today, eh Mark?

Nope, Just the small buttons on the I-Phone...

Posted by Martin McCaffery (Member # 37) on 07-22-2008, 09:34 AM:

I've been out of town, so getting in late with this observation. I remember seeing Casino Royale in digital. All through the film there was what I took to be a stuck pixel, red in this case. It was in the lower right section of the screen, so not a bother to anyone but me, but I fixated all the way through.
After the show, having read the credits and waited for the lights to come up, I looked at the screen (no curtains). The damn red pixel was still there!
I went for a closer look. It was a red Ju-Ju Bee someone had thrown at the screen.
I informed management, but have no idea if it was ever removed.

Posted by Jim Cassedy (Member # 4115) on 07-22-2008, 09:59 AM:

Great story about the Ju-Ju Bee!

During a digital screening I went to see last year, I was constantly annoyed by a small "bright" pixel just to the right-center of the screen. It wasn't very big, but being a projection-guy I couldn't ignore it no matter how hard I tried.

At the end of the show, as the credits were rolling my friend, sitting next to me, asked how I enjoyed the movie. I told him it was OK execpt for that damn tiny "hot-spot".

He had no idea what I was talking about, and sure enough - - if I moved one seat to the left or right it disappeared.

It turned out to be a shiny metal screw or bolt that was part of the the screen frame or speaker platform, and I was sitting in the EXACT spot that caught the light as it reflected back through the screen.

Posted by Tim Reed (Member # 137) on 07-22-2008, 01:22 PM:

quote: Frank Angel
At least with a 35mm film projector, you don't expect to find its weaknesses showing up this early on.

You haven't been on many new installs, have you? [Wink]

Posted by Mark Gulbrandsen (Member # 72) on 07-22-2008, 09:26 PM:

Martin,

That really is hilarious. It'd be funny of it was the same thing at the Century they're making fun of in this thread....

Mark

Posted by Aaron Haney (Member # 747) on 07-23-2008, 12:34 AM:

If it were anything on or behind the screen, it would have been visible during the pre-show, which (as I already stated) it wasn't.

quote: Mark Gulbrandsen
their film presentations must have really sucked

As far as I know this theater never had any. It opened just a few months ago as an all-digital installation.

quote: Jack Ondracek
You got your passes. Just go to a different screen.

Don't worry, I will. No need to get angry. My primary purpose in posting this thread is to find out more information, not to embarrass the theater management. I included the theater / auditorium info mainly in case anyone wants to go see for themselves.

quote: Mark Gulbrandsen
The integrator could have easily caused that problem. If you've ever seen an integrator fail you'd know what I mean.

Ok, but I was asking about the lens, which you mentioned earlier. Were / are you referring to a lens that is part of the integrator, or the lens on the front of projector (which I thought at first, hence my confusion). Also, if this were a problem with the integrator, which if I'm not mistaken comes before the DLP chips in the light path, would the dot not be attenuated by the DLP chips whenever the image turned dark? Also, wouldn't it be white instead of blue in that case?

Posted by Tristan Lane (Member # 1169) on 07-23-2008, 12:48 AM:

I'll chime in here.

Although I've seen a similar effect from a cracked integrator, it affected a larger portion of the screen, but still showed the effect of of a stuck pixel. Aaron is correct in his assumption that if it were in fact an integrator rod that was the cause, it would be attenuated during dark scenes.

Calling it a stuck pixel is still pure speculation. Any number of things could be causing this problem. A Formatter interface board, formatter cable, or the formatter itself may be the problem. The DMD chip may be operating properly.

If I were to troubleshoot the problem, I'd disconnect the blue formatter from the EFIB and then run a test pattern to see if the problem remains.

Hell, it could just be a piece of reflective crud sitting on the Laminar of the chip.

Posted by Mark Gulbrandsen (Member # 72) on 07-23-2008, 08:41 AM:

quote: Aaron Haney
Ok, but I was asking about the lens

Sorry Aaron... I have yet to see the result of say getting a drop of oil or grease on the actual front or rear lens element itself however like Tristian, I would lastly suspect the DMD itself.

Mark

Posted by Bruce Hansen (Member # 281) on 08-15-2008, 05:55 PM:

From something said at the SMPTE meeting here in Atlanta, stuck pixels are not uncommon, and (most of the time) can be fixed by putting up a gray screen on the projector. This causes the pixels to be on half the time, and off the other half. This exercises the pixel hinges, any (hopefully) will un-stick the pixel.

Posted by Thomas Pitt (Member # 4322) on 10-01-2008, 05:40 PM:

The pre-show wasn't affected but the trailers were? If it was the projector, you'd think that a stuck pixel would affect both. Or are they running the commercials on film and then switching over to digital for the feature, like some UK cinemas do?

The best way to fix a stuck pixel, other than returning the unit, is to try 'exercising' it like others have said. But instead of using a gray screen, find out the approximate coordinates of the stuck pixel and feed a rapidly changing image just to that area. There's a program called JScreenFix for computers that does a similar thing; I'm sure you can find out a way of doing the same for cinema DLP projectors.

It's not foolproof though. I have an LCD monitor that's got a stuck blue pixel; it's had it from the very day I got it - and JScreenFix didn't help.